Many diesel engines utilize a common rail fuel system where a common rail supplies high-pressure fuel to associated fuel injectors via branch passages that typically extend through the engine head. These branch passages typically include a specialized pipe, which is often referred to as a quill. The quill may include a rounded end received by a conical seat of the high-pressure fuel inlet port of the fuel injector and another high-pressure fitting connection or seat at its opposite end to connect to the common rail.
At present, due in part to the ever increasingly stringent emissions standards, manufacturers of fuel injectors are trying to design and manufacture engines with lower emissions than before. One way to reduce emissions produced by engines is by operating fuel injectors at higher pressures. Due to the increased costs associated with operating at higher pressures, manufacturers of fuel injectors find it troublesome to produce streamlined fuel systems that can easily be modified to operate at higher injection pressures if required. Furthermore, manufacturers may find it problematic to replace the older fuel systems with these newer fuel systems inside the engine without major modifications to the engine.
There have been attempts in the past to operate fuel injectors at higher pressures. One way to operate at higher pressures is to use an intensified fuel injection pressure. U.S. Pat. No. 3,453,875 by Mahr describes a fuel injection system that uses a pressure step-up unit. In the Mahr reference, the fuel injector includes a pressure step-up unit that allows for injection of fuel at either the common rail pressure or at an intensified pressure. The Mahr reference contemplates the possibility of a pressure intensifier unit outside the fuel injector, but does not show or suggest where or how an external intensifier could be incorporated into its system.
Engine manufacturers may have customers in different jurisdictions that have different emission standards. The cost of manufacturing engines may be kept low by manufacturing engines with as many common engine parts as possible, including parts associated with the fuel system. However, being able to manufacture engines that may meet the emission standards of different jurisdictions while using as many common engine parts as possible to keep manufacturing costs low may also be problematic.
The present disclosure is directed to overcoming one or more of the problems set forth above.